The invention relates to staplers, and more particularly to paper guides on staplers for aligning and locating papers to be stapled.
Heavy duty staplers typically include a base that supports an anvil. The anvil is configured to receive and clinch the ends of the arms of a staple passing through the sheets being stapled. A paper guide is typically coupled to the base to help align multiple sheets being stapled and to locate and position the sheets with respect to the anvil so that the staple is properly located relative to the sheets.
Prior art paper guides are typically movable relative to the anvil to facilitate different stapling jobs. Typically, the paper guide is coupled to the base for sliding movement with respect to the anvil along the base. One common prior art paper guide mechanism includes a rod extending through a slot in the base. A coil spring surrounds the rod and is retained on the rod at one end by a stop washer and at the other end by the underside of the base. The spring is compressed between the stop washer and the base such that the paper guide is biased into frictional engagement with the base, thereby tending to keep the paper guide from sliding freely with respect to the anvil, but allowing the paper guide to be moved manually if sufficient force is applied to overcome the friction. Corresponding detents and projections formed on the paper guide and along the base provide a variety of different xe2x80x9cset-pointsxe2x80x9d that can be used for the paper guide.
Other prior art paper guide mechanisms are more difficult to adjust. With these paper guides, the rod extending through a slot in the base is threaded, and a fastener such as a wingnut or a hex-nut is provided under the base to more positively lock the paper guide into place relative to the anvil. Typically, the nut is tightened against the underside of the base such that the paper guide cannot slide at all. To adjust the position of the paper guide, the stapler must be turned over and the nut must be loosened. With the nut loose, the paper guide and rod are free to slide in the slot to the new desired position. The nut is then tightened to lock the paper guide into its new position.
Yet another type of prior art paper guide mechanism replaces the rod configurations described above with a projection having a lateral aperture. The aperture receives a metal strip (i.e., a metal leaf spring) configured to bias against and frictionally engage the underside of the base on either side of the slot. The strip functions much like the spring described above to keep the paper guide from sliding freely with respect to the anvil, but allowing the paper guide to be moved manually if sufficient force is applied to overcome the friction.
The prior art paper guide mechanisms present various problems. The manually-slidable guides often get moved unintentionally when a stack of papers is inserted into the stapler for stapling. The friction force created by the spring or the metal strip is simply not large enough to prevent unintended movement of the guide. As the stapler gets older, the spring force of the spring or strip may also decrease, making unintentional movement of the guide even more problematic.
While the prior art guides having nuts or similar fasteners on the underside of the base will create more positive locking to substantially prevent unintentional movement of the guide, they are difficult and burdensome to adjust. The user must turn the stapler over, grasp the nut, loosen the nut either manually or with a tool, slide the paper guide to the new desired position, and finally tighten the nut without moving the paper guide from the desired position. This operation must be completed while holding and orienting the stapler with both hands.
The present invention overcomes these and other problems and provides an improved paper guide for a stapler. The paper guide of the invention can be quickly and easily adjusted between substantially locked positions without accessing the underside of the stapler. Furthermore, unintentional movement of the paper guide during stapling operations is substantially eliminated.
More specifically, the invention provides a stapler including a base having a top surface, a bottom surface, and an anvil. The stapler further includes a paper guide coupled to the base and movable relative to the anvil between a first substantially locked and immovable position and a second substantially locked and immovable position, without requiring access to the bottom surface of the base.
In one aspect of the invention, the paper guide includes a body portion supported on the top surface of the base. The body portion includes a paper guide portion. A locking member is coupled to the body portion and operable to substantially lock and unlock the body portion for movement relative to the anvil, without requiring access to the bottom surface of the base. The locking member is preferably at least partially sandwiched between the body portion and the base and includes a projection. At least one of the top surface and the body portion includes a ramped surface such that the locking member is movable between a locked position, where the projection is engaged with the ramped surface, and an unlocked position, where the projection is not engaged with the ramped surface.
In another aspect of the invention, the base further defines a longitudinal axis and includes a slot extending between the top and bottom surfaces in the direction of the longitudinal axis. The paper guide further includes a pin coupled to the body portion and extending through the slot to guide the movement of the body portion in the direction of the longitudinal axis. The locking member is preferably a lever coupled to the body portion and pivotable about the pin.
The invention also provides a method of adjusting a paper guide on a stapler. The stapler includes a base having a bottom surface, and the paper guide includes a body portion and a locking member movable relative to the body portion. The method includes moving the locking member relative to the body portion to an unlocked position without accessing the bottom surface, moving the body portion relative to the base, and moving the locking member relative to the body portion to a locked position.